The Feasibility of Extracting Low-Level Wind by Tracing Low-Level Moisture Observed with GOES-7

Abstract

The feasibility of extracting low-level wind (mean within the layer 700 hPa to surface) by tracking low-level moisture patterns observed with GOES-7 is studied. It is found that low-level wind can be inferred by tracking features in the moisture pattern that appear as brightness temperature difference (BTD) between the split-window (11- and 12-µm channels) images over cloud-free areas. It is also possible to track moisture features apparent in the enhanced infrared image, when cloud-free areas have a significant amount of water vapor. Both winds infused using BTD images and using enhanced infrared images show reasonable qualitative agreement. This technique is valid over the cloud-free ocean areas. Statistics show that the level of best fit for the wind using BTD images is 825 hPa and the magnitude of the vector errors are about 5.2 m s?1. This low-level wind error is comparable to that of wind estimates based on low-level cumulus cloud drift measured using time sequences of infrared images.